From: John Fastabend <john.fastabend@gmail.com>
To: daniel@iogearbox.net, ast@kernel.org, andrii@kernel.org,
jakub@cloudflare.com
Cc: john.fastabend@gmail.com, bpf@vger.kernel.org,
netdev@vger.kernel.org, edumazet@google.com
Subject: [PATCH bpf v3 2/3] bpf: sockmap, do not inc copied_seq when PEEK flag set
Date: Mon, 25 Sep 2023 20:52:59 -0700 [thread overview]
Message-ID: <20230926035300.135096-3-john.fastabend@gmail.com> (raw)
In-Reply-To: <20230926035300.135096-1-john.fastabend@gmail.com>
When data is peek'd off the receive queue we shouldn't considered it
copied from tcp_sock side. When we increment copied_seq this will confuse
tcp_data_ready() because copied_seq can be arbitrarily increased. From]
application side it results in poll() operations not waking up when
expected.
Notice tcp stack without BPF recvmsg programs also does not increment
copied_seq.
We broke this when we moved copied_seq into recvmsg to only update when
actual copy was happening. But, it wasn't working correctly either before
because the tcp_data_ready() tried to use the copied_seq value to see
if data was read by user yet. See fixes tags.
Fixes: e5c6de5fa0258 ("bpf, sockmap: Incorrectly handling copied_seq")
Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
net/ipv4/tcp_bpf.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 81f0dff69e0b..327268203001 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -222,6 +222,7 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk,
int *addr_len)
{
struct tcp_sock *tcp = tcp_sk(sk);
+ int peek = flags & MSG_PEEK;
u32 seq = tcp->copied_seq;
struct sk_psock *psock;
int copied = 0;
@@ -311,7 +312,8 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk,
copied = -EAGAIN;
}
out:
- WRITE_ONCE(tcp->copied_seq, seq);
+ if (!peek)
+ WRITE_ONCE(tcp->copied_seq, seq);
tcp_rcv_space_adjust(sk);
if (copied > 0)
__tcp_cleanup_rbuf(sk, copied);
--
2.33.0
next prev parent reply other threads:[~2023-09-26 3:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-26 3:52 [PATCH bpf v3 0/3] bpf, sockmap complete fixes for avail bytes John Fastabend
2023-09-26 3:52 ` [PATCH bpf v3 1/3] bpf: tcp_read_skb needs to pop skb regardless of seq John Fastabend
2023-09-26 3:52 ` John Fastabend [this message]
2023-09-26 3:53 ` [PATCH bpf v3 3/3] bpf: sockmap, add tests for MSG_F_PEEK John Fastabend
2023-09-29 8:02 ` [PATCH bpf v3 0/3] bpf, sockmap complete fixes for avail bytes Jakub Sitnicki
2023-09-29 15:10 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230926035300.135096-3-john.fastabend@gmail.com \
--to=john.fastabend@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=edumazet@google.com \
--cc=jakub@cloudflare.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).